I agree with Veggie, that looks like a lot of flame and velocity for such a small heater. You even see at a few places flame being reflected back down alongside the burner. This indicates that the flow out of the burner is exceeding the flow capacity up thru the central burner chimney past the turbulators
How much water is in the tank and how much fuel are you burning per hour.
Efficient transfer is all about surface area, temperature difference/turbulence(which maintains greater temp difference) and time. That water heater, I am guessing was originally gas fired? It had a much smaller burner and used natural draft to pull the hot gas from the burner up thru the turbulators so it was probably pretty efficient, btu in-btu out. With that ammount of flame, I am guessing you are putting a lot of heat out of the top. It will probably make the same ammount of hot water in a given timeframe with the burner at the lowest reliable setting as ti will at the highest. Of course it will use less fuel to do so...
The problem with the Babbington burner I run is getting a small stable flame. Below a certain point it dosn't like to stay stable. For my garage heater I just ran with the larger stable flame(smallest that would remain stable) and made a 6' long heat exchanger...
I havn't tried a burn chamber type like Glort has in his videos. I wonder how low you can turn the fuel and air and still maintain clean stable combustion. I am also curious how you deliver the fuel? I see the metal oil pipe entering the horizontal air pipe, but where does it end in relation to the burn chamber?
The good thing about the babbington is with a little preheat to the oil line with a torch it lights clean. I keep heating the oil line coil occasionally which is in the heated airstream. After bout 30-40 seconds of running I turn the outside blower on which forces fresh air over the heatexchanger and it starts delivering warm air immediately. The warm air then takes over pre-heating the oil as it rises to near 300F...
